Locknut



p 68 KAT'SUHIKO WAKABAYASHI 3,400,742

LOCKNUT Filed Jan. 5, 1968 KATSUHIKO WAKABAYASNL INVENTOR BY wmidu miATTORNEY$ United States Patent 3,400,742 LOCKNUT Katsuhiko Wakabayashi,Osaka, Japan, assignor to Takeji Wade, Osaka, Japan Continuation-impartof application Ser. No. 545,961,

Apr. 28, 1966. This application Jan. 3, 1968, Ser.

2 Claims. (Cl. 151-30) ABSTRACT OF THE DISCLOSURE A locknut comprises anut body and a ring of an elastic material. The upper periphery of thenut body is provided with a protrusion having a groove for receiving thering. The ring has a diametrically opposite pair of pawls and adiametrically opposite pair of cut out portions. The ring is so disposedthat the uppermost cut end of the screw thread of the nut may bepositioned beneath the central portion of either of the pawls to permitthe upper surface of the thread of the bolt engaged with the nut to bepressed by the pawls.

REFERENCE Part of the subject matter of this application is acontinuation-in-part of my 'copending application Ser. No. 545,961,filed on Apr. 28, 1966, now abandoned.

The present invention relates to an improvement of locknuts.

A principal object of the present invention is to provide a locknutwhich allows unforced and easy screwing when it is screwed on to boltand which works to positively and stubbornly prevent itself frombecoming loosened once the nut is screwed on to a bolt.

Another principal object of the present invention is to provide alocknut which allows a pair of engageable pawls of an elastic ring usedin combination with the nut to be effectively pressed against the uppersurface of the screw thread of a bolt to be screwed into a nut therebyto facilitate the screw engagement between the nut and the bolt,effecting firm locking action therebetween without causing damage to thescrew thread of the bolt and yet making itself serviceable over a periodof repeated use.

Other objects and advantages of the present invention will becomeapparent from the following detailed description with reference to theaccompanying drawings, in which:

FIG. 1 is a plan view of a locknut in accordance with the presentinvention;

FIG. 2 is a view in cross section along the line 2--2 in FIG. 1;

FIG. 3 is a plan view of a locknut in accordance with the presentinvention; as a pawl of a ring therein not positioned on the uppermostcut end of the screw thread of the nut;

FIG. 4 is a view in cross section along the line 44 in FIG. 3;

FIG. 5 is a fragmentary view in cross section of a locknut in accordancewith the present invention, showing the nut engaged with a bolt;

FIG. 6 is a fragmentary view in cross section showing the nutillustrated in FIGS 3 and 4 being engaged with the bolt;

FIG. 7 is a view in cross section showing an embodiment of a locknut inaccordance with the present invention as adapted for use as a cap nut;and

FIG. 8 is a partially sectional view showing the nut of the subjectinvention provided with a cap.

Referring to FIGS. 1 and 2, there is shown a nut body 1 having anannular protrusion 2 formed in the peripheral ice edge of the uppersurface thereof, the inner circumferential surface of said protrusion 2being provided with an annular groove 3 in which is mounted a ring 4formed of an elastic thin plate for locking the nut body to a bolt,whereby the ring is secured to the nut body as a unitary structure. Apair of diametrically opposite pawls 5 and a pair of similarly disposedcutout portions 6 are formed along the inner periphery of the ring 1,with the boundary between each adjacent pawl 5 and cutout portion 6located on the imaginary lines radially extending from the center of thering 1 and quadrisecting it, each of said pawls 5 and cutout portions 6thus having an equal peripheral width. When the ring 4 is to be mountedon the upper surface of the nut body 1, the ring 4 is so disposed thatthe uppermost cut end 8 of the screw thread of the nut may be positionedbeneath the central portion of either of the pawls of the ring 4. Thesignificance of this positioning in the locknut of the present inventionwill gradually be understood from the description hereinafter set forth.

When a locknut A thus constructed is brought in engagement with a bolt7, the screw thread of the bolt 7 driven upward in engagement with thethread of the nut body is further led upwardly from the upper surface ofthe nut, at first at the uppermost cut end 8 of the nut body 1. At thistime, since the ring 4 of the present invention is mounted on the uppersurface of the nut body in advance so that the uppermost cut end 8 ofthe screw thread of the nut body may be positioned beneath the centralportion of either of the pawls 5 in the ring 4, the uppermost cut end ofthe screw thread of bolt 7 contacts said pawl 5 simultaneously uponreaching the upper end of the nut body in engagement with the thread inthe nut body. As the nut is further rotated, the bolt 7 is drivenupward, forcibly pushing up the pawl 5 of the elastic thin ring with itsupper end surface of screw thread thereof, with the result that the pawl5 presses against the inclined upper surface of the screw thread of thebolt with its repulsive force to thereby restrict free rotation of thelocknut A. Further as the nut is moved forward in engagement with thebolt, the other pawl 5 is brought in contact with the inclined uppersurface of the screw thread of the bolt, an operation similar to that ofthe above-described pawl is thereby performed. In this way, due to thepressure P exerted by the pawls 5, repulsive force P is created to theinclined lower surface of the screw thread of the bolt and sandwichessaid screw thread of the bolt elfectively whereby the nut is firmlysecured on to the bolt. Since the pawls 5 in this case bear again thescrew thread of the bolt on its inclined upper surface in surface tosurface contact from above, there is no possibility of damaging thescrew thread of the bolt and repeated use of the bolt is thereforeensured.

The above-described operation and effects of the locknut in accordancewith the present invention is solely attributable to the fact that, asaforementioned, the ring is mounted on the upper surface of the nut insuch a manner that the uppermost cut end 8 of the screw thread in thenut body may be positioned beneath the central portion of either of thepawls 5. FIGS. 3, 4 and 7 for instance, illustrate an undesirable casein which the ring is so disposed that the uppermost cut end 8 of thescrew thread of the nut body may be located between the pawls of thering, namely, beneath the cutout portion 6. In the engaging operation inthis case the uppermost cut end of the screw thread on the bolt drivenout from the upper surface of the nut at the uppermost cut end of thescrew thread thereof does not at first abut the pawls of the ring, butis further rotated a distance B shown in FIGS. 3, 4 and 7, whereupon itis brought into engagement with the pawl 5 for the first time. The

rotation of the nut or of the bolt for the said distance B means thatthe uppermost cut end of the screw thread on the bolt has been moved toan upper position so much distance from the upper surface of the nutbody. Accordingly, at the time the uppermost cut end of the screw threadof the bolt is brought in contact with the pawl 5, the cut end ispositioned above the pawl 5, the pawl 5 thus being located between theridges of the screw thread of the bolt as shown in FIG. 7 withoutproducing effective locking action which is attainable by the presentinvention. Considering such a case, it will readily be understood thatthe position of the pawls of the ring previously described is essentialin the present invention.

Furthermore, in addition to the above described structure a locknut ofthe present invention is so constructed that the diameter C of animaginary circle involving the inner edges of the pawls of the ring isslightly larger than the root diameter of the thread on the bolt.Therefore, when the locknut is screwed on to the bolt, the inner edgesof the pawls are entirely prevented from abutting the roots of thethreads on the bolt with the result that the damage to the thread of thebolt is eliminated while the nut can readily be screwed on to the bolt.

While it is desired that the pawls bearing against the upper surface ofthe screw thread on the bolt for screwing the nut to the bolt beprovided with strength and resiliency balancing each other, the pawls ofthe present invention can be formed with great ease and each of thepawls can readily be given identical strength and resilience since thepawls are provided diametrically opposite to each other with anotherpair of opposite cutout portions disposed adjacent thereto, said pawlsand cutout portions each having an equal inner peripheral length.Moreover, the pawls, having no recesses in the base portions thereof,can maintain satisfactory strength.

Furthermore, the present invention can also provide a cap nut whichcomprises a cap 11 formed of a thin metal material in hemisphericalshape and having a fastening edge 10 radially and outwardly extendingalong the peripheral portion thereof, said fastening edge 10 and thering 4 being firmly secured to the annular groove 3 formed in the innercircumferential surface of the annular protrusion of the nut body 1.According to this embodiment, advantageous results can also be obtainedas in the above-described locknut.

What I claim is:

1. A locknut comprising a nut body and a ring formed of an elastic thinmaterial, said nut body having an annular protrusion formed in theperipheral edge of the upper surface thereof, and a penetrating holeprovided longitudinally in the central portion thereof, the innerperipheral surface of said hole being provided with a screw threadhaving an uppermost cut end, said ring being firmly secured to theuppersurface of said nut body by the outer circular edge thereof beingmounted in a groove formed in the inner circumferential surface of saidprotrusion, and having a pair of diametrically opposite axially flexiblepawls and a pair of diametrically disposed cutout portions formed alongthe inner periphery of said ring between said pawls with the boundarybetween each adjacent pawl and cutout portion located on imaginary linesradially extending from the center of said ring and therebyquadrisecting said ring, each of said pawls and cutout portions havingan equal peripheral width, the diameter of an imaginary circle involvingthe inner edges of said pawls being larger than the root diameter of ascrew thread of a bolt but less than the crest diameter thereof, saidring being mounted on the upper surface of said nut body with saiduppermost cut end of the thread on said nut positioned beneath thecentral portion of one of the two pawls, whereby at the time when a bolthaving a screw thread with a forwardmost cut end is screwed on to saidnut body and is driven upward on the screw thread of said nut body andreaches the upper end of said nut body, the uppermost cut end of thethread on said nut and the forwardmost cut end of the thread on saidbolt meet each other in a position beneath with the result that, uponsaid nut or bolt being further rotated, the forwardmost cut end of saidbolt contacts the under surface of said one pawl and moves upwards,forcibly pushing up the pawl with the inclined leading surface of thescrew thread of said bolt thus permitting the pawl to effectively pressagainst the inclined leading surface of the screw thread of said boltwith the repulsive force of the pawl in surface to surface contactthereby preventing free rotation of said nut without causing damage tosaid nut.

2. A locknut as claimed in claim 1, wherein in the groove formed in theinner circumferential surface of the annular protrusion of said nutbody, a cap and said ring are securely mounted together, said cap beingformed of a relatively thin metal material in hemispherical shape andprovided with a fastening edge radially and outwardly extending alongthe peripheral portion thereof.

References Cited FOREIGN PATENTS 3/1958 Germany. 6/1943 Great Britain.

